Material requirements planning system and procedures for use in process industries

Abstract

A system for controlling the flow of semiconductor products and their components through a production facility including assembly and final testing of a large number of different products with multiple product grades. The system stores information on the demand and inventory of all product grades together with grade distribution data giving the yield of all co-products of a product family from testing the common component of that family. The system includes means for calculating the number of common components to be tested to cover the requirements for all co-products of a family. The distribution data also gives the yield of all by-products of a test for particular products, and the system operates to adjust the inventory status for other products corresponding to such by-products, to avoid excess production of such other products in meeting projected demand. For cases where the data indicate for any product family a surplus of a higher grade and a shortage of a lower grade, the system includes means to decide whether to downgrade a portion of the higher grade to the lower grade; the projected inventory status of each grade is adjusted accordingly.

What is claimed is: 
     
       1. In combination in a system for controlling the flow of a plurality of products and components thereof through the assembly and testing procedures of a manufacturing operation comprising plural sequential process steps, including the development of an assembly and test schedule for the successive periods of a forward planning time frame, and wherein the products are arranged in families comprising different grades meeting respective performance specifications corresponding to different quality ratings, said system including data file means for storing information representing the inventory status of each product grade and the expected demand for each product grade during each of said periods, said system being of the type which is arranged to make calculations with respect to such stored information so as to determine the net requirements for each product grade during each of said successive time periods; that improvement to such system wherein said data file means stores grade distribution information giving the co-product yield for each grade of each product family from testing the common component of the product family; and   said system further comprising means to calculate, based on said grade distribution information, the number of such common components to be tested for each of said periods in order to meet the net requirements projected for the co-product grades for those periods.   
     
     
       2. A system as in claim 1, wherein said data file means further includes stored by-product information giving for at least certain of the products the identities and percentages of items which will be produced as by-products when testing for any particular one of said certain products selected; said system further including means to calculate and to store for a projected test of such particular product the number of each such by-products to be produced; and   means responsive to such stored by-product number data for updating the effective inventory of a corresponding item when the net requirements for that item are being developed subsequently.   
     
     
       3. A system as in claim 1, including means operable in making said calculations with respect to said stored information, for determining the net requirements for at least two grades of the same product family, to downgrade a surplus portion of the higher of said grades to the lower grade so as to minimize the need for additional assembly or testing to produce the lower grade. 
     
     
       4. A system as in claim 3, wherein said downgrading decision is made by taking into account the relative demands and yields of the two grades. 
     
     
       5. A system as in claim 1, including means operable, in calculating said number of common components, to decide whether to downgrade a portion of a higher grade to cover the requirements for a lower grade of the product family. 
     
     
       6. A system as in claim 5, wherein the downgrading desicion is based on the relative demands and yields of the two grades. 
     
     
       7. In combination in a system for controlling the flow of a plurality of products and components thereof through testing procedures of a manufacturing operation comprising plural sequential process steps, said system including means for developing an assembly and test schedule setting forth the planning goals for each of the products for the successive periods of a forward planning time frame, each of the products being required to meet respective performance specifications to be designated as such product, said system including data file means for storing information representing the inventory status of each product and the expected demand for each product during each of said periods, said system being of the type which is arranged to make calculations with respect to such stored information so as to determine the net requirements for each product; that improvement to such system wherein said data file means stores information giving for at least certain of the products the identities and yields of items which are expected to be produced as by-products when testing for any particular one of said certain products, said items corresponding to other products being manufactured in said manufacturing operation;   means to calculate, based on said by-product information, the number of such by-product items which will result from testing for such particular product; and   means for adjusting the effective inventory data for said other products in accordance with said by-product number data.   
     
     
       8. In combination in a system for controlling the flow of a plurality of products and components thereof through the assembly and testing procedures of a manufacturing operation comprising plural sequential process steps, including the development of an assembly and test schedule for the successive periods of a forward planning time frame, and wherein the products are organized in families comprising different grades meeting respective performance specifications corresponding to different quality ratings, said system including data file means for storing information representing the inventory status of each product grade and the expected demand for each product grade during each of said periods, said system being of the type which is arranged to make calculations with respect to such stored information so as to determine the net requirements for each product grade during each of said successive time periods; that improvement to such system comprising means operable in making said calculations with respect to said stored information, for determining the net future requirements for at least two grades of the same product family, to downgrade a surplus portion of the higher grade to the lower grade and to adjust the effective inventory of both grades.   
     
     
       9. A system as in claim 8, including means responsive to the relative demands and yields of the two grades for making the decision as to whether to downgrade. 
     
     
       10. A system as in claim 9, wherein said responsive means comprising means to calculate, for the two products, the following: ##EQU2## where I is a counter beginning with a current week W N is a total number of periods (weeks) in a plan   D I  is a demand for the grade in the period   B I  is a by-product supply in the period   Y is a yield to the grade   (N-I+1) is a factor which gives greater weight to near term demand than future demand.